In many cases, factoring an expression can make it easier to evaluate as in the following...

In many cases, factoring an expression can make it easier to evaluate as in the following applications.

Tubular fluid flow: As a fluid flows through a tube, it is flowing faster at the center of the tube than at the sides, where the tube exerts a backward drag. Poiseuille’s law gives the velocity of the flow at any point of the cross section: , where R is the inner radius of the tube, r is the distance from the center of the tube to a point in the flow, G represents what is called the pressure gradient, and η is a constant that depends on the viscosity of the fluid. Factor the right-hand side and find v given R = 0.5 cm, r= 0.3 cm, G = 15, and η = 0.25.